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Pulsing lights at idle - how old is this regulator??

2124 Views 56 Replies 10 Participants Last post by  matnetik
Here’s what I know - lights pulse at idle - will get some video this weekend.

I believe it’s just the headlights, not sure if it’s inside as well
3 wire alternator, new cables (unsure how old it is but keeps everything charged and battery reads 13.5v atm)
New solenoid and new battery
New instrument panel regulator
New ground strap from alternator to block, from block to firewall and to radiator
All new bulbs and light housing / cleaned connectors
Just ordered a new headlight switch because mine has been a bit finicky.

I am thinking it’s this 40+ year old voltage regulator or is this a replacement? Easiest way to test? Or just replace? Any recommendations for a solid state unit? Doesn’t need to look factory or anything but would love plug and play. As always, thanks!
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The obvious thing that jumps out at me from the photo is the missing condenser for the voltage regulator (the yellow plug with nothing attached). The voltage regulator constantly signals the alternator to charge, then cut-out as the voltage reaches its peak, then charge again. Each time the regulator "switches" the alternator off a voltage surge occurs as the circuit opens. The condenser is placed at that location to absorb the surge. It will also quiet radio frequency (RF) noise in the audio system caused by the "switching". The newer "solid-state" regulators are a bit more efficient than the older mechanical contact-point models but they still generate a surge upon switching.
Great replies and thanks as always! Will start by getting this thing a better ground, and I’ll pull the cover off to see what’s underneath. @Woodchuck (I owe you multiple beers at this point haha) can you point me in the direction of what condenser I need? @awhtx & @Hemikiller appreciate the link, not trying to cheap out so will buy the good one!
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Okay! Took the old regulator out today and installed a new Autolite from NPD, also got the suppressor and correct mounting bolts. I have a new headlight switch I also need to install - didn’t actually get a chance to test the lights since it was during the day but no issues on the install so there’s that - ha - will report back. Also had to take the old one apart just to see what was going on in there, look at those wound coils!
You'd be surprised to know that unless the relays and associated electronics are damaged, a bit of dressing of the contacts with a point file and some adjustments will bring that regulator back working just fine and dandy.
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Installed the new headlight switch (this needed to happen regardless, was hard to get the dash lights on because the old unit was finicky), new ground from block to firewall, VR is grounded properly, ground to radiator support and the lights are still pulsing in Drive or Park with the engines RPM.

I suppose next test is the alternator? I have a new battery, need to check voltage off and on with the car as well. I recently replaced all the wiring for the alternator, starter and solenoid / coil.

Time to check the alternator diodes. Grab your multimeter and set to a low-range AC volts scale and put the probes on the battery posts with the engine running. You should see NO AC voltage.
Well I am assuming this answers my question on the alternator?

With the engine on the DC fluctuates between 14.8 up to 16V
AC fluctuates between .1 and .5V

I suppose the next question is, if I were going to replace the alternator, which one? I would want to go with PowerMaster for sure but there are so many to choose from! If I understand correctly, this is a 3G alternator setup?
I'm not concerned with the marginal AC voltage as much as the high DC voltage. I wouldn't want to see DC voltage much exceed 14.7v at the battery terminals at 1,500 rpm or so. You might want to check out a different brand VR. If you decide to go with an alternator swap, I'd go with a 93-95 Aerostar 95A 3G unit with internal regulator... pretty much a direct bolt-in with some minor wiring changes.


I did start the engine seconds before taking this video so it was nowhere near warm but yeah pretty wild changes there. Going to run to UPS and will measure again once I return to see if there is any changes when warm.

I am all good with wiring, that's my speciality, you wouldn't recommend the Powermaster units? I've read good things about them, just curious. The VR is this one from NPD - VOLTAGE REGULATOR, ALTERNATOR - #10316-2A - National Parts Depot
Never had an experience with Powermaster.... I just like to utilize OE-replacement type stuff 'cause I don't know if Powermaster just buys the same stuff and puts their label on it. lol. Same for voltage regulator.... I'm sure AMK doesn't make the "guts"... I just buy an ordinary Standard Motor Products VR166 and swap covers if I want to "fool people".
I recently replaced the wiring on my alternator and it has three wires going to it - wouldn't a 3G alternator just be plug and play at this point? I am slightly confused on the difference between 1G and 3G, always though it had to do with the wiring
The 3G (Third Generation) Ford alternator is a bit different than the 1G (First Generation). The 3G has an internal cooling fan, versus the external one on the 1G and an "on-board" internal voltage regulator. When replacing the 1G with a 3G, the external voltage regulator can be removed as well as the wires between the regulator A+ (battery) and F (Field) and, if equipped with an alternator warning lamp, the S (Stator) and the alternator. The GRN/RED wire that went to the regulator I (Ignition) for vehicles with warning lamps or the S (Stator) for vehicles with ammeters is extended over to the new 3G alternator's "I" connection. Use the existing alternator output wire from the alternator BAT to the starter solenoid. This will retain your warning lamp or ammeter function. The one "hitch" is in the "excite" wire or the above-mentioned GRN/RED wire that you extended... If you have an AMMETER and the new 3G alternator fails to "go into charge mode" you'll need to place a load in the circuit, the easiest way is to add something like this in series...
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Ah, fully understand now. Is there any reason I would need to go to a 3G? Powermaster makes a 7078 1G 55-75 Amp unit for $140 bones and it's a simple replacement. I have factory A/C, radio with 5 speakers and electric power steering. Wondering if this is enough or should I go the 3G route - just asking questions here!
The 3G is more efficient and will charge better at low rpm. A 55A should do just fine with EPAS.
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I did measure when I first started the car and the voltage was all over similar to the old alternator...
Which it will do as the regulator cuts in and out to keep the alternator from overcharging. Since you've switched to a lot of LED's you've reduced the load on the charging system to where the regulator is "cycling", recognizing an almost fully-charged battery....

Let my brain think for a minute... you said your alternator had 3 wires... a big one to the BAT post, a ground and one to the FLD post.... is that correct? That means you should have an ammeter in your instrument cluster and the GRN/RED wire to your voltage regulator goes into the "S" location? I wonder if your solid-state regulator has enough resistance in the "sense" circuit..... I'd be tempted, if you have a test light, to see what happens when you hook your alligator clip to ground and back-probe the "S" plug on the regulator with the test light.... with the engine idling, to see what it does for the "pulsing"....
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The only things that aren’t LED are the headlight bulbs and the fog light bulbs. Everything else is LED.

And correct on the three wires, BAT, ground and FLD. I do have an Ammeter (doesn’t really do much other than sit in the center haha,, probably just need to scrub the connectors). I have a test light, will give this a shot and see what happens. Thanks for the quick response here as always -

I’d love to just make what I have work if possible but ultimately if the 3G solves the issues I am 100% okay going that route. Given that I have tried a new alternator, replaced the VR and noise suppressor I would think that might be the next step. I would try headlight relays or replace the harness but given that ALL my lights pulse I think there is something else going on.
FWIW, the lights "pulse" in my '05 Magnum R/T and have since the day it was new... 140k later and it still does it, with the original alternator.
Was about to put the old alternator back in, but before I do I decided to look at the wiring from the regulator - does anyone know if this is correct?

Well a quick search shows that yes, this is correct for a 68’ with an Ammeter - will try to back probe the green/red wire now -

No change on back probing the green/red wire. Question though, is the orange wire supposed to have any power? With ignition on or off the orange cable shows nothing, assuming this signals when the charge is happening - Just tested resistance and it is wired to the field post on the alternator which I believe is correct.

Yellow and green/red both show 12.8 v
The wire to the FLD post only receives current when the regulator signals the alternator to charge. This wire is responsible for sending current to the alternator rotor field windings, creating a magnetic field so that, as the rotor rotates and passes by the stator coils, an output current is generated.
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-original BAT wire from car is taped off and not being used
Do you have battery voltage at the "A" terminal on your dummy regulator?
Will check tomorrow after the rain, I am assuming that the “A” terminal runs parallel with wire that was previously connected to the alternators BAT meaning I need to connect it to the B+ terminal on the alternator? I saw someone did that in this thread and it worked for him - thanks for the late reply
See the splice in the original harness. The "output wire" from the alternator goes in 4 separate directions (regulator, inside the passenger compartment for the "feeds", the ammeter and to the battery, via the common lug on the solenoid. Lacking these splices in the replacement harness, wires need to go to a common point. In the case of the output wire these can be picked up at the BAT terminal on the alternator or the common lug on the solenoid. It doesn't matter which, other than for the ammeter.... The ammeter is a "special animal" as it's a shunt type and both wires going to the ammeter are exactly equal in length and the wire spliced to the alternator output is located at a point that effectively "zeroes" the gauge.
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Yellow or ”A” at VR is getting 12V with ignition on or off = Just the way it should be.
Green/Red “S” is getting 12V with ignition ON = Just the way it should be.
Orange ”F” is not showing any voltage regardless of ignition on or off (this is the wire that is attached to the PA Performance green/red wire on the harness) Not the way it should be.
Check the continuity between the FLD post on the alternator and the "F" terminal in the regulator plug. You should have less than 0.1 Ohm. I'm not familiar with the color codes used by the PA Performance harness, but there needs to be a direct connection between the regulator "F" and the alternator FLD.
I did test resistant a few days ago and can confirm the red/green or field from the alternator is the one going to F on the VR - will check again for continuity. I do have my electronic choke spliced into that line, wonder if that’s something to do with it? With the ignition on, the electronic choke is showing 12V.

maybe I should move the electronic choke to the stator wire (PA suggest this)
Choke should NOT be connected to the Field wire. Power in the Field wire, controlled by the regulator, tells the alternator to charge.
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Car "turns over" just fine...and WANTS to start. Did you pump the pedal once to set the choke?
Jumped to my other car, got battery voltage at 13.3 - still won't run, tried starter fluid in the carb and nothing. I am so beyond clueless as to what could be going on - double checked all grounds and wiring. I also tried jumping the electronic choke straight to 12v just while cranking to see if there was an issue there and no luck. I am honestly at the point of putting the old alternator back in and seeing if it starts. I don't understand why it wouldn't start considering changing the alternator shouldn't affect starting -

Getting some white smoke out of the exhaust and it smells like gas specifically. I could only assume it's beyond flooded at this point and maybe I just need to let it sit for a few days. Any help is much appreciated - all this to stop the lights from pulsing (I'm over here kicking myself haha)
Toss in a new set of plugs but, before you do, check dwell while cranking...
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